This proposed project is designed to evaluate the potential of pesticides such as parathion, carbaryl, toxaphene and pentachlorophenol in causing occupational respiratory diseases by studying the pulmonary effects of these pesticides during inhalation exposures. Groups of mice will be exposed in a head-only fashion to these pesticides at various concentrations, 4 hr/day for five days. The respiration of these mice will be monitored with body plethysmograph to determine whether these pesticides will cause sensory and pulmonary irritation. Intermittently during exposure, the presence of bronchoconstriction will be tested by the CO2 hyperventilatory response. Other toxicologic parameters that will be determined are body weight gain, hematocrit and the histology of lungs, liver and kidneys. For the parathion exposed group, inhibition of cholesterase in RBC and plasma will also be measured.